1. Field of the Invention
The present invention relates to a posture adjusting mechanism of a cargo handling device which is provided with an arm that can swivel on a horizontal plane and which is mainly provided on the bed of a cargo truck.
2. Description of the Related Art
Crane type cargo handling devices incorporated on the bed of a truck are known.
However, such conventional cargo handling devices have various drawbacks, so the present inventors have disclosed a cargo handing device for use in a cargo truck.
In the above cargo handling device, the rear end of a first arm member having a length smaller than the width of the front side of the cab of a cargo truck, is mounted on the upper surface of the cab through a vertical shaft in such a manner that the first arm member can swivel about the vertical shaft. A second arm member is turnably mounted on the distal end of the first arm member. A hoisting mechanism is mounted on the distal end of the second arm member to wind or unwind a rope member such as a belt which hangs from the hoisting mechanism. A cargo supporting portion is provided on the lower end of the rope member.
The present inventors have also proposed a cargo handling device for a cargo truck in which the hoisting mechanism is mounted on the rear end of the second arm member.
The latter cargo handling device exhibits excellent load balance in the lateral direction of the bed of the cargo truck. Furthermore, tilting the vertical shaft (mounting shaft), through which the rear end of the first arm member is mounted on the upper end of the pole member, in the lateral direction of the truck can be detected by an inclination sensor, and the pole member can be tilted in the lateral direction of the truck by operating a pivot mechanism provided within a pole mounting base through which the pole member is mounted on the bed upright on the basis of an inclination signal from the inclination sensor. Consequently, the mounting shaft can be maintained vertical even when the bed is tilted in the lateral direction thereof, and so-called arm flow phenomenon in which the arm members deviate in the lateral direction due to the tilting of the bed in the lateral direction can thus be prevented.
However, the latter cargo handling device also has the problem to be solved.
That is, in the latter cargo handling device, tilting of the mounting shaft caused by the tilting of the bed of the cargo truck in the lateral direction thereof can be corrected but tilting thereof caused by the tilting of the bed in the longitudinal direction thereof cannot be corrected. Consequently, the arm flow phenomenon in which the arm member with a cargo hanging therefrom deviates in the longitudinal direction of the bed due to the tilting of the bed in the longitudinal direction thereof cannot be avoided.
Particularly, flow of the arm in the longitudinal direction of the bed occurs during the cargo unloading or loading process in which tilting of the bed occurs gradually or when the cargo is loaded or unloaded from a cargo truck which is at a stop on a slope. In the latter case, the bed is tilted from the beginning of the cargo loading or unloading operation.
Furthermore, even though tilting of the mounting shaft can be corrected on the basis of the signal from the inclination sensor when the bed is tilted in the lateral direction thereof, it is troublesome to conduct correction operation during the cargo loading or unloading operation.